Lio Josse served as a Jedi within the ranks of the Jedi Order. Back in 232 BBY, Josse participated in the Jedi's mission to provide assistance to the agriworld of Hetzal Prime and its encompassing system amidst the chaos of the Great Hyperspace Disaster. Working under the coordination of Jedi Master Avar Kriss, the Jedi successfully used telekinesis to redirect a tibanna tank, preventing its catastrophic impact with the Hetzal system's largest star. This action saved the system, but Josse died due to the immense energy they expended in the process.
Lio Josse was a Jedi affiliated with the Jedi Order during the High Republic Era. They were involved in the galaxy-wide effort to save the agriworld of Hetzal Prime and its system during the Great Hyperspace Disaster in 232 BBY. Their mission was to avert a collision between a liquid tibanna tank and the Hetzal system's largest star, an impact that would trigger a destructive explosion capable of destroying the entire system.
With Jedi Master Avar Kriss providing coordination, Josse and numerous other Jedi throughout the galaxy joined their minds to divert the tank from its impending collision. However, as they channeled all their concentration into this task, any Jedi who weakened under the enormous pressure made the undertaking even more challenging. Although they successfully averted the crisis, Josse died because they were unable to maintain their own safety while exerting the effort to move the tank. Kriss sensed the Jedi's passing, acknowledging their loss with a brief mental recognition.
In 229 BBY, Harli Cogra, a Vurk Jedi Master, wrote a book titled Chronicles of the Jedi, which provided details on the Jedi of the High Republic Era. In the book's third chapter, Cogra mentioned the Jedi who had participated in Kriss' network to save Hetzal Prime, including those who had perished, such as Josse.
As a member of the Jedi Order, Josse was a Force-sensitive individual who was trained to use the Force to manipulate objects.
Lio Josse was initially mentioned in the novel Light of the Jedi, penned by Charles Soule, and indirectly in the young-readers book The High Republic: The Great Jedi Rescue, written by Cavan Scott. Both books were launched as part of Phase I of the Star Wars: The High Republic multimedia project on January 5, 2021. The character's name was first explicitly mentioned in Light of the Jedi.